lecture 20 Flashcards

sets of physiological and behavioral features that incorporate not only reproductive traits but also survivorship, length-of-life characteristics, preferred habitat type, and competitive ability

how populations grow and for the reproductive success of populations and species

-iteroparity versus semelparity

-continuous versus seasonal iteroparity

-R and K selection

-grime's triangle

a pattern when offspring are produced in a single reproductive event

successive years or breeding seasons

a pattern of repeated reproduction at intervals throughout the life cycle

species such as birds, mammals, or temperate forest trees have distinct breeding seasons that lead to distinct groups of individuals all born at the same time

for a few species, individuals reproduced repeatedly and at any time of the year (as well as some parasites, and some primates exhibit this strategy

the environments is stable, a single act of organism, will devote all energy in making offspring and not maintaining its own body

survival of juveniles is very poor and unpredictable, repeated/long reproductions will increase survival

stable populations adapted to exist at or near the carrying capacity, K, of the environment

high rate of per capita population growth, r, but poor competitive ability

continuum

most individuals die late inlife

individuals die at a uniform rate

most individuals die at a young age

are adapted to take advantage of habitat disturbance (annual plants adapted to colonizing disturbed areas)

are adapted to live in highly competitive but benign [not harmful] environments (many tree species)

are adapted to cope with extreme environmental conditions such as high soil salt or temperatures that exist in salt marshes and deserts (mangroves and cacti)

plant life histories based on a model in which stress, disturbance, and competition are the important selective factors (based on data in grime 1979)

evolution

20 months on average

25% longer than average

widely among different species

limited amount of energy to invest in survival, maintainance, and reproduction

-maximizes number of offspring surviving to maturity

-depends on likelihood of survival to different age classes

cells require repair and argued that narutal selection should favor levels of seld-repair that are good enough to keep an organism in sonund condition only for as long as it has a reasonable chance of reproducing

life history theory (island possums appeared to age slowly than the mainland possums)

guppies

compared guppies in streams with numerous predators to those in streams with few predators. fouund effect on number of offspring, offspring weight, and mean size at sexual maturity

rapid evolution of life history traits

expected directions

allocation of resources to one life history trait reduces investment in another trait

expense of growth or body maintenance

grew faster, bigger, and lived longer

-males have less investment

-males have uncertain paternity

-these roles reversed in some species

states that a 1:1 sex ration is an evolutionarily stable strategy, but not all individuals are able to mate at all times

is the ratio of male to female individuals who are available for reproducing at any given time (sexual selection becomes an important agent when members of one sex compete with each other to mate)

mean number of mates per females

males choose to mate with only a few high-quality females, eggs from larger females are more likely to develop into viable offspring

-miscarriage

-cannibalism

maximize fitness

found youn female red-winged blackbirds produced more females, while order females produced more male

these adjustments increase the proportion of offspring surviving

-production of each sex favored when rare

-rare sex has more mating opportunities

sex ratio stabilizes (natural selection will favor mutant females that produce more males)

shifted back to it by natural selection

offspring

often exhibit haplodiploidy (haploid males, diploid females) so females can alter sex ratio of offspring by choosing whether or not to fertilize eggs with sperm (fig wasps produce fewer mles with larger clutches)

states that parents in good condition tend to bias their offspring sex ration toward the sex with a higher variation in reproductive values, whereas parents in bad condition favor the opposite sex

-produce females when in poor condition; daughters will likely have some offspring even if in poor condition

-produce males when in good condition; males likely to benefit more from being large and will more readily attract mates

trivers-willard-predicted manner (start as females and breed as such when young and small, but switch to male when they are large)

-with high resources females favored

-up to three helping daughters beneficial

-with low resources males favored

-disperse away from poor habitat

differ for the sexes

consequently, male-only care, female-only care and biparental desertion all occur

occurs when parents benefit from withholding parental care from some offspring and invest in other offspring

attention with loud begging calls and bright red mouths

appear black, influencing parental feeding rates (sibling competition in American coots)

occurs when sibling compete for parental care for parental care or limited resources (in some cases it can lead to siblicide/the killing of another sibling)

effect on the phenotype of an offspring caused by an allele inherited from a particular parent (ex. hinny: result of horse stallion + female donkey)

occurs when genes inherited from one or the other parent are silenced due to methylation (offspring express either maternal or paternal copy of gene, but not both)

the process by which methyl groups are added to certain nucleotides (associated with altered gene expression)

imprinting genes evolved through conlfict between parents which is resolved in their offspring

is a conflict between the fitness effects of alleles of a given locus on mals and females

deterioration in the biological functions of an organisms as it ages (cells accumulate malformed protein, immune less effective, etc)

slow the aging process (genes involved in repair switched on under stress

worm mutants that age more slowly have lower fitness

lifespan (promoting either aging ot longetivity) in Caenorhabditis elegans

some that encode yolk proteins and insulin-like INS-7

age-related declines in survival and reproduction respectively (the rule in free-ranging populations of vertebrates

the decrease in the force of natural selection inevitably leads to actuarial senescence in any age-structured population, but does not adress reproductive senescence

declines as a function of age

selection is weak and ineffective at maintaining survival, reproduction, and somatic repair at old age

aging evolves because selection cannot efficiently eliminate deleterious mutations that manifest themselves only late in life

aging evolves as a maladaptive byproduct of selection for increased fitness early inlife, with beneficial early-life effects being genetically coupled to deleterious late-life effects that cause aging

selection fo an increased number of lifetime reproductive events (balance with pros and cons)

risk of reproduction at older age selects for reduced fertility (investment in current offspring)

loss of fertility associated with shift in investment to grandchildren

long-reproductive lives